The present invention relates to an interchangeable finder type camera which is provided with an exposure coupling or interlocking device for transmitting diaphragm aperture information from the diaphragm ring of an interchangeable objective lens to an exposure control device provided in an interchangeable finder.
In general, in order to provide an exposure interlocking coupling in an interchangeable finder type camera, it is necessary that a drive coupling element of the diaphragm ring be positioned within the movable range of follower member of the interchangeable finder, which follower member is biased or urged to so move. However, since the recently developed exchangeable finder type camera is of such a construction that the interchangeable finder diaphragm ring follower is urged merely in one direction, such that if the interchangeable finder is mounted, with the interchangeable objective lens being mounted, then the drive coupling element of the aforesaid interchangeable lens will be positioned out of the movable range of the biased follower member of the finder, so that the finder follower member will not be brought into engagement with the drive coupling member of the diaphragm ring, thereby failing to effect an exposure interlocking state. Accordingly, it sometimes occurs that a photographer is under the mistaken impression that the exposure interlocking state has been effected in the camera, due to the fact that the interchangeable finder has been mounted thereon and he thus takes a picture under improper exposure conditions.
In addition to the above, complicated operations are required for achieving an exposure interlocking state, such as for instance, the interchangeable objective lens must be removed prior to mounting of the interchangeable finder, the finder being then mounted and thereafter the objective lens is mounted so as to position the drive coupling element of the interchangeable objective lens within the movable range of the follower member of the interchangeable finder which is urged in an advance direction.